Side-by-side reference

Understand the difference.

Compare the meaning, drawing context and source references of two entries. A similar graphic or shared abbreviation does not establish equivalence.

First referenceCompare with

FCU

Symbols

Fused connection unit plan mark

A fused connection unit, often called a fused spur, connects a fixed appliance such as a towel rail, extractor fan or boiler directly to a final circuit through a small cartridge fuse. Plans commonly draw a small square with an S-shaped fuse mark or the letters FCU at the wall line, sometimes with a switch stroke for the switched type.

Drawing use: GA
Application: Installation & communications
Reference family: IEC

A distinction that matters

A switched socket outlet accepts a plug; a fused connection unit is wired to fixed equipment.

Full reference

SSO

IEC

Switched socket outlet

A switched socket outlet combines the outlet and a single-pole or double-pole switch in one accessory plate. On the plan the outlet half circle carries a short switch stroke with a tick, borrowed from the light-switch form, showing that the user can interrupt supply at the outlet without removing the plug.

Drawing use: GA
Application: Installation & communications
Reference family: IEC
Form evidence: Switched socket outlet. IEC 60617 installation-plan style (architectural and topographical installation symbols); independently drawn, not certified IEC geometry or a database identifier.

A distinction that matters

A socket outlet with interlocked switch prevents plug insertion or withdrawal while energised; a plain switched outlet only lets the user switch the supply.

Full reference

Original educational previews. Follow the source references on each full entry for the appropriate standard or selected product.